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High-precision Error Model And Mitigation Technique For GNSS Receiver In Multipath Environment

Posted on:2021-01-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:C J MaFull Text:PDF
GTID:1488306548491954Subject:Information and Communication Engineering
Abstract/Summary:PDF Full Text Request
With the developing applications of global navigation satellite systems,including positioning,navigation and timing,the requirements for uses' observation accuracy have become much higher,and the meter-level pseudo-range accuracy or centimeter-level carrier phase accuracy can no longer meet the increasing needs of high-precision users.Even worse,satellite navigation receivers are affected by multipath signals in urban,mountain,jungle,and sea environments.Based on the high-precision application of satellite navigation,this thesis models and analyzes the sampling error and multiple errors in the navigation receiver,and achieves the following innovative results:(1)Aiming at the problem of insufficient resolution of digital code phase discriminator,this thesis studies the modeling and mitigation technology of resolution error.By establishing a code phase resolution error analysis model,a set of error evaluation indicators that can be independent of spreading codes are proposed.By theoretically analyzing the code phase resolution of digital correlator and digital discriminator,a non-commensurate sampling parameter design method which can limit the resolution error to the smallest is proposed.By improving the mode of random phase jitter,a resolution error smoothing method based on periodic phase jitter is proposed,which can further reduce the resolution error.(2)Aiming at the problem of zero-bias of the digital code phase discrimination curve,this thesis studies the zero-bias error modeling and mitigation technology.Based on the long-period spreading code signal,a statistical error analysis model of zero-bias error is established,and a set of evaluation indicators that are independent of the spreading code and the initial phase of signal are proposed.By theoretically analyzing the statistical characteristics of errors,a zero-bias error suppression method based on dual sampling is proposed.By analyzing the double estimation loop of the Binary Offset Subcarrier(BOC)signal,it is found that the subcarrier modulation can effectively suppress the zero-bias error.For example,by measuring the subcarrier phase of BOC(1,1)signal,it is possible to reduce the zero-bias error by about 87.76%.(3)Aiming at the deviation of code phase measurement caused by multipath fading,this thesis studies the pseudo-code multipath suppression technology based on the code loop discriminator design.By establishing a pseudo-code multipath error analysis model,a set of evaluation indicators that can be used to guide the design of code loop discriminator is proposed.Through the general characterization of the local code reference waveform,a design method of pseudo-code anti-multipath reference waveform that can satisfy multiple constraints is proposed.Given priority to anti-multipath or anti-noise,the reference waveform examples CRx-16 and CPx-16 are designed respectively.In order to balance the performance of anti-multipath,anti-noise and stable tracking,a multi-reference waveform based pseudo-code multipath error estimation method is proposed,which can independently implement code phase tracking and multipath error estimation.(4)Aiming at the deviation of carrier phase measurement caused by multipath fading,this thesis studies the carrier multipath suppression technology based on the carrier loop correlator design.By establishing a carrier multipath error analysis model,a set of evaluation indicators that can be used to guide the design of carrier loop correlator is proposed.Through the general characterization of the local code reference waveform,a design method of carrier anti-multipath optimal reference waveform is proposed.For different power loss,a set of reference waveform CWx-16 are obtained.In order to balance the performance of anti-multipath and anti-noise,a carrier multipath error estimation method based on multi-reference waveform is proposed.The results shows that the proposed method can reduce the carrier phase multipath error of 73.8% when the gate width of the reference waveform is 0.125 chips,effectively increasing the receiver carrier multipath rejection.The main research results of this thesis can guide the high-precision measurement and anti-multipath design of the satellite navigation receiver.Part of the research achievements have been successfully applied to the development of different types of receiving terminals in the BDS-3.
Keywords/Search Tags:Global Navigation Satellite System, Code Phase, Resolution, Zero-bias, Carrier Phase, Multipath Mitigation
PDF Full Text Request
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